Centered mold for dental castings.



H. SGHWEITZER.

CENTERED MOLD FOR DENTAL GASTINGS.

APPLICATION TILED JAN. 6, 1914.

1,1 1 2,847. Patented Oct. (:3, 1914.

WITNESSES: b/ 7 tg/220R) HEINRICH SCHWEITZER, OF'NEW-YORK,- N. Y.

CENTERED MOLD FOR DEN'LAYL- CASTINGSL- Specification" of Letters Patent.

Patented Oct. 6, 1914.

Application filedlanuary 6, 1914. Seria1 No.-810,571.-

To alt w/wm it may concern:

Be it known that I, HEINRICH Sonwnrn Zen, :1. subject of the German-Emperor, re

siding at New'York, in the county and-State of New York, haveinvented new and useful Improvements in Centered Molds for Dental Castings, .of which the following is-a specification.

Molds for dental castinzgsheretofore as a rule were onlysurrounded by a mold ring or frame and a large part of-the upper surface of the mold investment-compound was subjected to the fluid pressure which is applied in the casting act.

It must be understood that thein-vestment compound for dental castings after-itis'annealed-forthe purpose of evaporatingwax patterns-consists of a veryporous mass and. that a ooddeal of-flu-id pressure medium enters t e pores onthetopsurfaoe of said mass when the mold is exposed to fluid pressure. This is a disadvantageas thepressure should act only in the central part-of the mold where in a: crucible themetal :is liquefied by heat.- Ainold flask with a. top surface reduced at right angles as shown in- Figurel of the accompanying drawing is objectionable because fluid pressure medium does enter the open spaces which are created between the moldand flaskby the metal expansion of the annealing flask. For large castings it is desirable to invest the wax pattern in a moldwhich is free on top and bottom. during the'process of annealing and to seal the peripheral part of these open surfaces d-uring the act of pressure application.

The object of my invention is to seal. the

peripheral part of the-top surface of a mold during. the act iof'pressure application by a detachable cover centering of themold upon a receptacle andthe base of acasting machine.

Fig. 1. of the accompanying,- drawing.

shows in vertical section a mold invested in a flask with the.topsurfacemeduced at right angles. Fig. 2 is a lateral view of-a cover rovidedewith' taperingsurfaces which. ena le at the same time the ed by a frame. Fig. 9 isa vertical section of a. receptacle for the mold. Fig. 10 shows in vertical section cover, mold with -framc, and receptacle. Fig. 11 shows in lateral view with parts in section a complete pressure. flaskwlpon the base of a casting machine.

Molds-having a diminished open surface ;on top -by reducing the surface at right angles such as for example is shown in Fig. 1 (A) of the accompanying drawino require the-annealing of the mold inthe rame, B, which is covering the peripheral part, P, of the moldd Annealing of the whole flask naturally ruinsafter a shorttimc the contact surfaces, the metallic parts expand by heat and a space, S, betweenmold and frame is created into which fluid pressure medium (gas, air) enters as soon as it is compressed against the mold. To obviate this I have constructed a-detachable cover of metal, Y, and a mold provided with tapering surfaces on top. The tapering surfaces, T, Fig. 7, preferably made of conical shape are intended to rest u 1 on the tapering surfaces, P of the mold, Fig. 8, thus sealing the peripheral .partwfthe mold. The conical top surfaces ,of the mold as shown in Fig. 3 represent the shape of-an ascending taper. The central ,part of the-cover may taper at a different angle but is concentric to the surface of the peripheral part. In the center of the cover is an aperture leaving uncovered the part of the mold which is occupied by the mold crucible, C, Fig. 8. In order to obtain a perfect adaptation of the mold cover upon the mold ,it is required to place the cover upon the mold iinvestment compound while the latter is in a plastic state or to pour investment compound against-the interior surface of the cover. The surfaces,- T, of the cover are oiled and separate after the investment compound of the-mold has set leaving as a result a mold with smooth tapering surfaces free on top. The detachable mold cover is readjusted over-the top surface of the mold after the latter is annealed and the metal is melted in the crucible. The cover is nowexposed to radiating heat but a few seconds during the pressure action and the tapering surfaces seal. the mold even in case of metal ex ansion.

he cover is provided with a tapering surface extension, K, Figs. 2 and 5, on the exterior surface in which it can be sealed against a head, H, Fig. 6. The lateral and bottom surfaces of the mold may have anysuitable shape; the mold is preferably surrounded by a round frame, F, Fi 8, which is restin in its lower margin, Il a, on the margin, l\ of a receptacle, R, Fig. 9. This receptacle, having a tapering surface extension, D, on the outside, is preferably provided with tapering surfaces; U, upon its open face and a mold prepared upon such funnel shaped face naturally has a tapering surface extension in the bottom which is centered upon the receptacle. The mold prepared to fit the receptacle and cover can be centered upon the base, M, of a casting machine by placing the receptacle in the recess, .V, Fig. 11, putting the pattern in the mold investment compound surrounded by the frame, F, and cover, -Y, in position, and lowerin the sealing head, H, before the plastic lnvestment compound has set. The tapering surface, K,'of the cover allows for the centering of the mold and flask; the

. tapering surfaces, T, seal the peripheral surfaces of the mold. No fluid pressure can act uponthe mold surfaces; pressure being concentrated upon the crucible part of the mold will force the liquefied metal from the central part to all directions desired and fill the mold cavity completely and most perfectly. The sealing head is connected with a source of fluid pressure, Z, and may have any suitable contact surfacefor making a seal with the mold cover. In the preferred construction, shown in Figs. 6 and 11, it is provided with tapering surfaces on the inside in order to make a seal with the outside taper of the mold cover. The head, H, is guided by the tube, 0, which is movin" up and down in the vertical perforation, V? leading through the bracket, L, of the base of the casting apparatus. The perfora tion, W, runs true concentric with the tapered recess, V, thus iving a concentric relation to the receptac e, R, andv head, H, between which mold and mold cover are centered.

Having now fully described my invention I claim:

1. In a device for dental castingsand the like the combination of a mold and a mold cover, said mold having ascending ta ering surface extensions on then per end or the purpose of'making a seal uring the act of fluid pressure application, said cover having a central aperture and tapering surfaces surrounding said a erture for sealing the tapering top sur ace of the mold. during the act of fluid pressure application.

sealing head provided with means for making a seal against said cover.

3. A flask for the preparation of a mold for dental castings and the like and for sealing a mold durin the act of casting consisting of a mold rame, a mold receptacle and a cover; said cover having a tapering surface extension with a central aperture and being provided with tapering surfaces on the lnside for the preparation of tapered mold surfaces.

4. In a devicefor dental castingsand the like the combination of a detachable mold having an uncovered tapering surface extension on the upper end, a base, a sealing head and a pressure flask consisting of a mold cover, mold frame and mold receptacle; said mold cover having tapering extensions on the interior surface for the formation of tapering mold surfaces, centering the mold and sealing the mold during pressure application in peri heralparts of the top sur ace, said cover a so provided with a central aperture and a tapering extension on the exterior surface surrounding the aperture for making contact with the sealing head, said sealing head connected with a source of fluid pressure and movably adjusted on the base in concentrical relation with said mold receptacle, mold and mold cover substantiall as described and shown.

5. In a device or dental castings and the like the combination of a mold, .a detachable mold cover and a sealing head connected with a source of fluid pressure; said mold having tapering surfaces on its upper end, said mold cover having tapering extensions on its interior surface for making contact and seal with the upper mold surface, a

central aperture and a tapering extension on its exterior surface surroundingv the aperture; said sealing head provided with tapering surfaces for making seal and contact with the exterior tapering surface extension of said cover.

HEINRICH SOHWEITZER. Witnesses:

WM. H. KRUBE, H. W. PnMBLnToN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of l atents,

. washingtomnc." 

